Hi,
check if al auto settings are turned of and maybe you need to do the brightlight trick.
The following is written freetracks handbook:

Webcam frame rate is lower than advertised.

*Turn off auto-exposure and manually reduce exposure (this is essential).
*Make sure your USB port is not less than a USB 2.0 port.
*Use a different USB port. Sharing ports or hubs with other devices can cause bandwidth bottleneck and lower fps.
*Disable anti-flicker/enable outdoors mode in your camera properties.
*Reduce video quality in the Stream property page if your webcam supports it.

My webcam's Auto-Exposure (AE) is on and the option is greyed out so I can't turn it off!

Try to enable the option by using Enable Button or WindowsEnabler for XP or VistaEnabler for Vista.

In the case of Microsoft VX-1000:
1. Set auto exposure on (default) and exposure value to 0 (or a little higher).
2. Place a bright light source, like a lamp, in the field of view of the camera so that it reaches 30fps.
3. Disable auto exposure with one of the enable button apps.
4. Switch the light off, the camera should still be producing 30fps and will continue to do so while the exposure settings are not changed.

I unboxed Simconnect in Freetrack, now nothing moves in P3d as I thought.
But the FPS are still about 10 in Freetrack.
I had Freetrack running while closing Prepar3d and it was 10 FPS until the game was closed. Then it went up to 30 FPS..